Electric timing device



Nov. 19, 1940. s. G. CRANE ELECTRIC TIMING DEVICE 3 Sheets-Sheet 1 Filed Nov. 8, 1937 Nov. 19, 1940. s. G. CRANE ELECTRIC TIMING DEVICE 3 Sheets-Sheet 2 Filed Nov. 8, 1937 INVENTOR SAMUE L G.CRA E NOV. 19, 1940. s CRANE 2,221,863

ELECTRIC TIMING DEVI CE SAMUEL G.CRANE 1 TURN Y5 Patented Nov. 19, 1940 UNITED STATES PATENT OFFICE ELECTRIC TIMING DEVICE Application November 8, 1937, Serial No. 173,435

8 Claims.

This invention relates to automatic timing dcvices for controlling electrical circuits, and aims to provide an improved electrically operable tim ing device which consumes very little current,

and is capable to handling loads without arcing or harmful sparking at the contacts.

Another important object is to provide llll proved means for timing cooking devices, and a novel automatic cooker for boiling foods and like for any predetermined length of time, the parts of which are so arranged that the current disconnected and the cooked matter raised from the water upon expiration of the time for which the device is set to run.

A further object is to provide an improved timing device which is capable of withstanding relatively high temperatures, and which also con-- tains no magnets and is accordingly operable in a magnetic field.

Still another object is to provide a timing device of the character indicated from which all springs are eliminated, and the working parts of which move slowly, and which accordingly may be operated without lubrication over long periods of time without danger of wearing out or of failore from other causes.

Still another object is to provide a timing device of the character indicated which may easily and quickly be set to run for any predetermined length of time, at the expiration of which it operates switching means to control desired circuits. A further object is to provide such a timing device which constantly indicates during its running the time remaining before operation of the switching means.

A still further object is the provision of a timing device of the character indicated having a constant load control circuit which cannot cause radio interference.

Another important object inheres in the provision of a control circuit incorporating the timing means, which circuit may be entirely independent of or shunted across the controlled feed lines.

Still another object is the provision in conjunction with my improved timing means of thermostatic overcontrol means usable in conjunction with electrically heated devices to prevent operation of the timing means until a predetermined heat has been reached, and which automatically initiates operation of the timing means upon attainment of such predetermined temperature, whereafter the timing means may assume control of the apparatus.

Other objects include structural embodiment of the invention in a cooking device so arranged that although an exposed heating element directly immersed in water to be boiled may be pro vided, is not possible to reach into the water or to add water to the receptacle, or otherwise to incur the danger of a shock while the current 5 is on.

Other objects and advantages will be apparent c the following description, wherein reference de to the accompanying drawings illustrat rred embodiments of my invention and similar reference numerals designate similar parts throughout the several views.

In the drawings:

Figure l is a perspective view of my improved timing device incorporating the principles of this 1 invention.

Figure 2 is a substantially central longitudinal sectional view thereof.

Figure 3 is a plan view of the mechanism with the cover removed and the timing dial partly broken away.

Fgure a is a view similar to Figure 3 showing only the escapement switch controlling means and also diagrammatically showing the connections of the various electrical elements.

Figure 5 is a schematic diagram of a somewhat modified embodiment.

Figure 6 is a perspective view of a food boiler provided with timing means constructed in accordance with this invention.

Figure 7 is a rear elevation view with the casing broken away showing the automatic elevating means by which the boiled matter is lifted from the water.

Figure 8 is a view thereof partly in section and partly in side elevation with parts broken away, and

Figure 9 is a diagrammatic view showing the connections of the several elements.

Referring now to the drawings, and particularly to Figures 1 to 4 inclusive, the improved timing mechanism will be seen to be mounted upon a base plate l0 which forms the back wall of a casing, the cover of which, designated I2, also carries some of the apparatus and is removably secured to the base plate. The timing means comprises an electrically controlled escapement mechanism arranged to throw a switch upon the expiration of a predetermined interval of time after the device is set in operation. The escapement wheel [5, which may of course be either spring or weight driven, is controlled in its rotation by a pallet generally designated I8. The pallet is pivoted to the base on a pin 20 and carries escapement pins 2l-22, alternately engageable in the conventional manner with the toothed periphery of the escapement wheel. The pallet is formed entirely of metal, except for escapement pin 2|, which is either formed of insulating material, as shown, or insulated from the pallet. Pin 22, however, is uninsnlated from the pallet. The escapement wheel is also formed of conductingmaterial and pivoted to the insulating base on a pin It. The driving means for the escapement wheel is shown as a torsion spring I! secured at its inner extremity to the pin and at its outer end reacting against the escapement wheel.

Aswitchannflisactuablebyapin it proiecting from the escapement wheel. The switch arm is normally in engagement with a flxed contact 21, but ls separable therefrom by the pin 20 as the escapement wheel completes its rotation. It will be recognised that the device might with equal facility be arranged to close a circuit rather than open it. Spring or weight means such as the torsion bar It urges the pallet to the left, as viewed in Figures 3 and 4. A hot wire II, which forms a part of a shunt circuit presently to be described, holds the pallet in the right hand posltlon, when the wire is cool and accordingly contracted. In such position the pallet is insulated from the escapement wheel by pin 2i. When the wire is heated, however, and expands suillciently, it allows the pallet to swing to the left until pin 2| frees the wheel, and it is causht by the escapement pin 22, which completes a circuit between the pallet and the wheel.

The wheel is urged clockwise by the spring l1, and comes to rest in the position in which it is shown in Figure 4 after having opened switch blade 26. The pallet arm II is formed of spring material and normally holds the escapement pins in a position to engage the escapement teeth, although the arm may be ilexed downardly to free the teeth from the wheel. The tops of the escapement pins are also so inclined that when the wheel is manually rotated in a counter-clockwise direction, the pins are forced downardly to permit such rotation by camming action, such movement being permitted by the flexibility of the pallet arm.

A dial it secured to and rotatable with the escapement wheel is visible through a window opening it in the cover l2, to indicate the setting of the wheel, and constantly shows the length of time which the device has yet to run to reach switch-open position. A knob 21 secured to the wheel and dial assembly and projecting from the cover of the casing allows counter-clockwise rotation of the dial and wheel to any desired set position. A trip pluger ll projecting from the face of the cover is so arranged that when depressed it may be made to engage and push down on the pallet arm, to free the escapement pins from the wheel II and allow the latter to spin instantly to switch-open position.

Referring to Figure 4, in which the connections are diagrammatically shown, current is supplied to the device through lead wires "-82. Wire ii is connected to the terminal post II and so to the hot wire 23. Such post is also connected to the escapement wheel ll through post It, as well as to the wire I. which from one of the outlet leads to the controlled apparatus. The other input lead, 52, is connected to switch contact 21, while to the other switch contact is connected the output lead It. The other end of the hot wire is connected to pallet arm ll, while the arm is connected, through wire I! with a load, indicated as an incandescent lamp II. The wire ll con-- nectstheotherterminalofthelamptotheoutput lead It.

The load represented by lamp II will be seen to beshunted acrosstheline,anditwiilbesesn that when the wheel is set, to move pin 20 away from switch blade 2', allowing the switch to close and imposing tension upon the spring I], the-current for the bulb it must pass through the hot wire 38, when insulated pin II is in contact with the wheel ll, while when pin 22 engages the wheel, the hot wire is short-circuited by the connection provided through the escapement wheel and pallet. The load of the lamp it may be very slight, just suiilcient to cause the wire ss to expand suniciently to allow the pallet to swing to the left under the action of spring 8.. Alternate swinging movement oi the pallet and controlled intermittent rotation of the unpement wheel will be seen to result, by reason of the fact that the wire. starting in cold position (andwithpin 2| insulatingthepalletiromthe wheel), is heated by the load as soon as switch 28-21 is closed. When the wire expands sumciently and the pallet moves to the left. the wheel is allowed to advance until the next tooth is caught by pin 22. Pin 22 provides contact between the wheel and pallet, short-circuiting the hot wire, which. relieved of its load, cools and contracts, again pulling the pallet to the right, allowing the wheel to advance until pin 2| catches the next tooth. Insulated pin 2i then breaks the short-circuit, again causing the wire to carry the shunt current. The wire then heats and reexpands, and the same cycle is repeated. This intermittent swinging of the pallet and rotation of the escapement wheel continues until the pin 26 strikes the switch arm 2!, breaking the circuit through both the main line and the shunt circuit which contains the load It.

Since the shunt load broken by pin 22 may be very light, and switch 25-21 which carries the main load is broken with a quick movement, and may incorporate relatively heavy contacts, the device will be seen to be capable of handling relatively heavy currents without arcing.

A mercury switch may of course be substituted for contacts 2l-2'l, as shownin the modified construction of Figure 5 or any other switch desired may with equal facility be actuated by the escapement wheel. Neither is it necessary that the controlling current for the timing circuit be from the same source as the controlled current. As shown in Figure 5, separate switches may be actuated by the escapement wheel, the switch "A being arranged to break the main line current. while a separate switch "-81 incorporated in the control circuit also breaks the latter when the wheel has reached the oi! position. The control circuit is shown as provided with a separate source of current, indicated as a battery II. and is entirely distinguished from the main controlled or feed circuit. Other portions of this embodiment have been given reference characters similar to those used in connection with the first embodiment, distinguished by the addition of the letter A to each. Weights (NA, NA) will beseentobeusedinsteadofspringstoactuate the pallet and the escapement disc.

A typical application of my improved timing device is illustrated in Figures 6, 7, 8 and I wherein is shown an automatic boiling device, particularly for eggs and other foods. Within the outer sheathing H0 and having its walls spaced therefrom is a boiling pot I". A basket-like tray "2 is slidable in the boiler from a level above is to one below the intended water level. The tray is carried by .a bifurcated vertically slidable arm I03 having one leg inside and one outside the boiler. At its top the tray supporting rod is provided with a knob I04 by which the tray may be pushed downardly. A hinged lid I05 is con stantly urged open by a spring I06 incorporated in its hinge, and an arm I08 projecting outwardly and downwardly from the top of the tray supporting rod I03 is engageable with the lid to close the same as the tray is lowered. The outer section of tray rod 03 slides in the space between the boiler and the outer wall I I0. Springs II 2 connected to the bottom of the outer leg of the rod, and to the casing, tend to lift the tray. At its bottom the outer leg of the rod carries an insulating cross-piece II3 through which extend metallic contactor studs H5. The studs are engageable with contact clips III to close the circuit to the heating element when the tray is depressed, and open the circuit when the tray is raised. The switching means thus provided is in series with the output lead 56 from the timing device to the heating element I20, the other out put lead 55 being connected directly to the heating element. Also shunted across the heating element is a hot wire I25 which expands when the current is on, to allow the latch piece M4 to engage and hold in depressed position the cross piece H3 and so the arm I03 and its attached tray I02. The spring portion I26 (or weight) which urges the latch-piece toward latching posi-: tion is normally restrained by the wire !25 from projecting the latch-piece to that position; the wire, when cold, being too short to allow such projection.

It will be seen that by turning the knob M to set the timing mechanism to run for a desired interval and depressing the plunger rod I03 by means of the handle I04 the circuit is closed to the heating element I20, through the switch por-i tions I I1 and the time device, which corresponds to the embodiment first described. The current also expands the wire I25, allowing the latch piece I24 to hold the tray in depressed position. The timing device maintains'this condition for a predetermined time, the lid being held closed by the arm I08. Upon the expiration of the interval for which the timer is set, the current supply to the heating element is interrupted, wire I25 contracts, freeing the latch from the tray arm and allowing the tray to be elevated by the springs II2 to a position above the water in the boiler and readily accessible from the open top, the lid I05 then being raised by the spring I06.

A switch I30 normally short-circuits and prevents operation of the timing mechanism, but is opened by thermostat I33, which is secured to the boiler and directly responsive to the temperature thereof, when the boiler reaches a predetermined temperature. Thus the thermostat I33 may be set to initiate operation of the timer upon attainment of the boiling temperature of water by the boiler, after which the heating will continue for whatever time the timing device is set to run.

While it will be apparent that the illustrated embodiments of my invention herein disclosed are well calculated to adequately fulfill the objects and advantages primarily stated, it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the subjoined claims.

What I claim is:

1. Electrically regulated timing means comprising in combination with current-supplying conductors, current controlling means in series with at least one thereof, and electrically controlled timing means for actuating said current controlling means comprising a rotatable memher, and means for rotating the same intermit tently and at a controlled rate, including a member expansible and contractible in response to passage of electric current therethrough and incorporated in a shunt circuit across said conductors, means responsive to expansion and contraction of said member for making and breaking a short circuit across said member, to cause alternate expansion and contraction thereof, a load in series with said last mentioned means and with said expansible and contractible member and also incorporated in said shunt circuit, said shunt circuit being connected to one of said conductors upon the side oi said current controlling means more remote from the source of current,

whereby the shunt circuit is broken when said same current controlling means is open.

2. In combination with a source of electrical energy and a plurality of current supplying con-= ductors connected thereto, switching means in series therewith, and timed operating means for controlling said switching means including an escapement mechanism, electrically operable means for controlling said escapement mecha nism, and a. separate circuit for supplying cur I rent to said electrically operable means; said. escapement mechanism comprising an escapement wheel, means for driving the same, a pallet member for controlling rotation thereof, and said electrically operable means comprising an electrically expansible and contractible member incorporated in said separate circuit for moving said pallet member, and means responsive to moving of the pallet member to make and break: a short circuit across said expansible and contractible member, to cause oscillation of current flow therethrough, and a constant load in said separate circuit in series with said last mentioned means and with said expansible and contractible member.

3. Timing means for an electric circuit, comprising an escapement wheel, means for rotating the same, a pallet member movable to control the rotation of the escapement wheel and having contact portions which alternately make and break an electrical connection between the pallet and escapement wheel during movement of the pallet, and operating means for the pallet in-- cluding a source of current, a motor element operable thereby and connected in circuit with said contact portions to be intermittently energized by the making and breaking of said electrical connection, said motor element being mechanically connected to the pallet to move the same intermittently whereby to control the rotation of the escapement wheel.

4. Means as set forth in claim 3 including a scale connected to said escapement wheel for indicating the position thereof, and means for manually turning the wheel to various set positions to fix the extent of movement thereof required to actuate said circuit controlling means.

5. Means as set forth in claim 3 in which said pallet member is laterally movable out of engagement with the escapement wheel to allow unrestrained rotation of the latter under the influence of said driving means.

6. Means as set forth in claim 3 in which said pallet is laterally yieldably movable away from the escapement wheel to allow unrestrained rotation thereof under the influence of said drivlng means, said pallet having wheel-engaging portions which normally rock into and out of engagement with said wheel. at least one of said portions having a surface so inclined that upon rotation 01' said wheel in a direction opposite to that in which it is rotated by said driving means. the pallet is'iorced away from the escapement wheel to allow such reverse movement oi the wheel.

'1. meanseseetiorthinclalmainwhichsaid' motor element comprises a member expansibie and contractible in response to electrically induced heating and cooling and mechanically connectedtothepallettorockthe samebyitsexpansion and contraction.

8. Electrically regulated timing means comprising in combination with current-supplying spouses conductors. current controlling means in series withat least one therec! and electrically controlled timing means for actuating saidcurrent controlling means comprising a rotatable mem- -berandmeansior rotating thesameintermitsaid shunt circuit.

SAMUEL G. CRANE. 

